Lactate dehydrogenase NADH dissociation rate constant

The results of stopped-flow studies of the lactate dehydrogenase reaction have proved to be more difficult to interpret than those of alcohol dehydrogenase. The dissociation velocity constants for the binary NADH compounds of the pig heart and skeletal muscle lactate dehydrogenases are much larger than that for liver alcohol dehydrogenase, and also larger than the maximum specific rates of lactate oxidation at pH 6.0-7.0 (Table VII). Some earlier step must therefore be rate-limiting. 

It is important to point out that the values of the rate constant for the dissociation of a ligand from its specific binding site, obtained by the two above methods (displacement and transfer), are not necessarily the same. Wu et a/. (1991) noted that the rate constants for NADH dissociation from its complexes with lactate dehydrogenase and glycerol-3-phosphate dehydrogenase are more than 50% higher when measured by ligand displacement... 

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